The project continues our investigations into the effects of bile acids and fatty acids on intestinal water and solute transport. Based on the information available, we developed several hypotheses about their mode of action. 1) The changes in water and solute transport induced by bile acids and fatty acids can be explained as the result of cyclic-AMP stimulated fluid secretion and altered mucosal permeability. 2) Their effectiveness is determined by their monomer concentration in mixed micellar solutions and their ability to interact with and bind to the intestinal brush border membrane. The experiments proposed test these hypotheses and their consequences in the small and large intestine, stomach, and gallbladder. Experiments conducted will be in vitro studies and in vivo perfusion studies in experimental animals and man.